CHANGES IN THE ULTRASTRUCTURE OF LAMB MUSCLES AS INFLUENCED BY FREEZING AND SODIUM TRIPOLYPHOSPHATE (STPP)

Abdel-Aal, H.A., Mohamed, H.M.A.

Abstract
Three lamb muscles from shoulder, Supraspinatus (SS); lion, Longissimus dorsi (LD) and leg, Biceps femoris (BF) were kept in refrigerator at 4°C for 24 hr, dipped in 10% sodium tripolyphosphate (STPP) solution for 1 min and frozen at - 18°C or at - 40°C for 48 hr. Proximate composition, phosphorus, drip loss, cooking loss, pH and water holding capacity (WHC) were determined. Ultrastructure of treated and untreated muscles was studied using transmission electron microscopy (TEM). No significant (p<0.05) differences were found between moisture, protein and fat content of the three lamb muscles. Muscles treated with STPP had higher phosphorus content than that of untreated muscles. Treated or untreated frozen lamb muscles at -40°C had lower drip losses and cooking losses than those frozen at -18°C. All three lamb muscles treated with STPP had lower drip losses and cooking losses and higher pH and WHC than those of untreated ones. Results of the study suggested that STPP increased the pH, improved the WHC and decreased drip loss and cooking loss of frozen lamb muscles. Freezing at -40°C and STPP treatment maintained the well-defined all sarcomere components of lamb muscles compared to untreated muscles and frozen at -18°C.

Key words: Lamb meat, water-holding capacity, sodium tripolyphosphate, transmission electron microscopy

MODIFICĂRI ULTRASTRUCTURALE ALE MUŞCHILOR DE MIEL, SUB INFLUENŢA CONGELĂRII ŞI A TRIPOLIFOSFATULUI DE SODIU (STPP)

Abdel-Aal, H. A., Mohamed, H. M. A.

Rezumat
Trei muschi prelevati din carcasa de miel, de la nivelul spetei, Supraspinatus (SS); cotletului, Longissimus dorsi (LD) si jigoului, Biceps femoris (BF) au fost conservati prin refrigerare la 4°C timp de 24 h, fiind apoi imersate în solutie de tripolifosfat de sodiu 10% (STPP) pentru 1 minut si congelate la temperaturi de -18°C sau de - 40°C pentru 48 ore. Au fost determinate compozitia chimica, continutul în fosfor, pierderea prin exsudare, pierderea prin procesare si capacitatea de retinerea a apei (CRA). Ultrastructura muschilor tratati sau netratati cu STPP a fost studiata prin microscopie electronica cu transmisie. Nu au fost identificate diferente semnificative (p<0.05) legate de continutul de apa, proteine sau lipide a celor trei muschi studiati. Muschii tratati cu STPP au prezentat un continut mai ridicat de fosfor decât cei netratati. Muschii congelati la -40°C au prezentat valori mai reduse pentru pierderile prin exsudare si procesare, fata de cei congelati la -18°C. Muschii supusi tratamentului cu STPP au avut pierderi mai mici prin exsudare sau la procesare si valori mai mari pentru pH si CRA, comparativ cu muschii netratati. Rezultatele studiilor au sugerat faptul ca STPP aplicat înainte de congelare a determinat cresterea valorii pH, a îmbunatatit CRA si a redus pierderile prin exsudare sau la procesare. Congelarea la -40°C si tratamentul cu STPP au mentinut intacta si bine definita structura componentelor sarcomerelor, comparativ cu muschii netratati si conservati prin congelare la -18°C.

Cuvinte cheie: carne de miel, capacitate de retinere a apei, tripolifosfat de sodiu, microscopie electronica cu transmisie